The following is a list of frequently asked questions regarding calibration and our services. If the information you need isn’t supplied here, Contact Us and we’ll be happy to answer any questions you may have.

Why do I need to Calibrate my Equipment?

Over time, the base accuracy (a known value) of your tester can change. This can occur for various reasons from a sudden surge of electricity to damage to the meter’s internal operation caused by accidental knocks. When this occurs, the meter’s accuracy ‘drifts’ from its normal state causing your instrument to become inaccurate.

Calibration is the process of checking that your instrument is operating at the correct level of accuracy. If there’s a slight imbalance, a calibration technician will fix it and restore the meter to its correct working order. Similarly, if errors are being caused by faulty internal parts, calibration can help to discover and subsequently repair these issues.

In short, you need to calibrate your equipment as it could be inaccurate and this may lead to the incorrect installation of equipment or an inability to identify faulty installations.

How often should I calibrate my instruments?

The vast majority of instruments should be calibrated annually although there are exceptions. Test instruments should also be calibrated if you suspect readings may be inaccurate or out of specification.

Annual calibration is required even if the meter isn’t used frequently as factors such as moisture and low temperature can affect operation. Therefore, if you’re going to use the test instrument again and the certificate has expired, it requires a calibration.

What is the difference between UKAS and Standard Calibration Certificates?

Standard (Traceable) Calibration Certificate

  • Reports the values and differences between the reference equipment and your test equipment (Unit Under Test - UUT)

UKAS Calibration Certificate

  • Reports the values and differences between the reference equipment and the UUT using configurations of test equipment that have been evaluated and approved by UKAS.
  • The degree of uncertainty of the measurement for these configurations has been determined.
  • Values, differences, and uncertainties are noted on the calibration certificate.

Which calibration certificate do I Need?

Where the application is not ‘critical’ e.g. a general office situation a traceable calibration may suffice.

Where the application is ‘critical’ e.g. highly regulated sites (Hospitals, MOD etc) a UKAS calibration would be most probably a requirement by your client.

Guidance should be sought from those that have defined the process and are aware of the regulatory environment of the site.

How quickly can I have my test equipment back?

We understand how important it is to get your equipment back to you when you need it. So, we’ve created a ‘Turnaround’ service to meet your needs with three options to choose from:

Standard – Five working days

Express – Three working days (Additional £15)

Lightning – One working day (Additional £25)

Our ‘Turnaround’ clock starts ticking the moment your test equipment arrives at our laboratory.

What about bank holidays and weekends?

As you would expect, bank holidays and weekends are not considered working days, so please allow extra time when calculating the return of your equipment.

How much will calibration cost?

The price we charge for calibration is extremely competitive and depends upon the type of instrument, the speed of service selected and the certificate you require. You can view our prices online here

Who will test my equipment?

ElectriCALibration delivers the highest quality service. Your equipment will be tested at Avon Dynamics by highly qualified and dedicated experts in electrical testing and inspection within a UKAS approved testing and calibration laboratory meeting BS EN ISO/IEC 9001 Quality Management Systems accreditation. The laboratory is authorised to issue UKAS certificates.

Why should I use the ElectriCALibration service?

Simply because this service has been created using our extensive knowledge of the sector over many years specifically for busy electricians and the electrical market. It’s the fastest, best value, online calibration service in the UK.

What if my instrument fails calibration?

When you send in your instrument, you should also provide any leads, chargers or accessories that are used with it. We recommend this because a lot of faults with instruments can be found in their leads. By using your leads/accessories to calibrate your test equipment we can find problems that may otherwise go undetected.

If your meter fails the calibration process, this generally means there is a fault with the unit. If there’s a problem, we will contact you to discuss the options. If we’re able to repair your instrument, the repair department will supply you with a quotation for repair.

If we are unable to repair your unit, we can supply a wide range of new test equipment at highly competitive prices. We hold stock of most items and can usually have a new machine with you the next working day.

Does calibration affect the memory on a tester?

Nothing we do in our calibration procedure will affect your tester’s memory in any way. All your results will still be stored on your instrument.

Nevertheless, we recommend that you download all your results before sending your test meter for calibration. As, for example, if your instrument requires repair and we need to replace components/boards then we cannot guarantee that test results will be retained.

What is Electrical Calibration?

Electrical calibration refers to the process of verifying the performance of, or adjusting, any instrument that measures or tests electrical parameters. This discipline is usually referred to as dc and low frequency electrical metrology.

Principal parameters include voltage, current, resistance, inductance, capacitance, time and frequency.  Other parameters, including electrical power and phase, are also in this segment of metrology.  Ratio metric comparisons of similar parameters are often performed to compare a known parameter to an unknown similar parameter.

Electrical calibration involves the use of precise devices that evaluate the performance of key properties for other devices called units under test (UUTs).  As these precise devices have thoroughly known performance characteristics compared to the UUT, performance evaluation and/or calibration adjustment of the UUT to identify or minimize errors is possible. Typically, the performance of such precision devices should be four or more times better than the UUT. 

These precision devices fall into two broad categories. Electrical signal sources are often referred to as either calibrators or standards. Precision measurement devices are often classified as precision digital multi-meters, measurement standards, or ratio bridges.

Calibrators and standards

A calibrator is usually able to provide a wide range of precision output signals, such as voltage settings ranging from as little as a few microvolts, increasing through several decades of millivolts, and volts, up to a common maximum of about one kilovolt.

Additionally, modern calibrators commonly provide outputs for various electrical functions such as voltage, resistance, and current.

A standard is considered more precise than a calibrator. It is capable of performance that is four or more times better than a calibrator. However, this improved performance is usually limited compared to a calibrator. Often, a standard can provide only one electrical function, and with only a single output setting, or a few output settings

Precision digital multi-meters, measurement standards, and ratio bridges

Precision digital multi-meters (DMMs) provide excellent measurement performance of various electrical parameters through a number of decades of values. Measurement functions usually include voltage, current, and resistance. Less commonly, frequency, capacitance and others can also be included. 

The higher performance category of a measurement device is termed a measurement standard, or possibly even a measurement bridge. These devices commonly have fewer functions but better performance than precision DMMs.

For correct calibration, there are additional needs beyond using precision devices to evaluate the UUT. These precision devices must themselves be routinely calibrated in a manner which agrees with (or is traceable to) an international standard of the parameter being evaluated. This is evidenced through an unbroken chain of documented comparisons with increasingly better standards. Eventually this chain of compared standards includes a recognised national, international, or intrinsic standard.

Selecting a solution

The workload for dc and low frequency ac electrical metrology can include a wide variety of test and measurement instruments:  digital multi-meters – analog or digital;  bench or handheld  – oscilloscopes, ScopeMeter® Test Tools; power and energy meters; RTD and thermocouple thermometers; process instrumentation; data loggers; strip and chart recorders.

The functions of the calibrator must meet all, or essentially all, of the test equipment functions being calibrated. Crucially, the calibrator must have better performance than the required test specifications of the workload.

The normal rule of thumb is that a calibrator or standard must be four or more times better than the specification being evaluated for performance, or the specification referenced for an adjustment process.

Successful selection of a calibrator involves a thorough analysis of the specifications of both the equipment to be tested and the calibrating standards. This analysis is usually based on the manufacturer’s recommended specifications for the tested equipment versus the standard specifications of the calibrating instrumentation.

The term compliance describes the amount of electrical drive a calibrating source can provide to the electrical load created by the measuring instrument being tested.

A calibrator has a specifically limited drive while not compromising the accuracy of its signal. Certain test instruments (e.g. certain analog meters and panel meters) are relatively large loads and require significant electrical drive from the calibrator. Therefore, compliance is an important consideration within specification performance.

Measurement and sourcing

Calibration involves both types of applications where precision measurement and precision sourcing are required. A precision source is used to test a measurement instrument, and a precision measurement device tests a sourcing instrument. Good metrology incorporates quality assurance programmes that check laboratory calibration instrumentation.

A laboratory should therefore be equipped with precision measurement instruments with similar performance specifications to the lab’s precision sourcing instruments (both by functionality and spec). Routine comparison will then ensure confidence in the consistency of the lab’s instruments and detect problems early so corrective actions can be taken. It is considered best practice to use both categories of instrumentation in a calibration facility.

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